Birthweight, rapid growth, cancer, and longevity: a review.

The fetal growth restriction hypothesis states that retarded growth in utero promotes health problems later in life. While most of the studies on intrauterine growth retardation (as measured by birthweight) confirm this hypothesis, many researchers have found flaws in these studies. In addition, many studies have found either no correlation or a positive relation between birthweight (BW) and adult blood pressure or mortality. Furthermore, high BW leads to greater adult obesity and chronic disease, and increasing macrosomia in newborns raises the risk for birth-related problems. Increased cancer risk is also tied to higher BW, and catch-up or accelerated growth generally has negative health effects. Adult height has been found to correlate with greater BW and birthlength (BL), and several studies have found an inverse relation between height and longevity. Paradoxical findings, such as lower BW and low levels of cardiovascular disease in the developing world, are presented. Within 25 years, genetic engineering will allow in utero alterations to the fetus, resulting in higher BW and taller adults. The authors suggest that increased BW leading to larger adult body size has dangerous implications in terms of human health and survival.